The present invention relates to a virtual machine system and, more particularly, relates to a virtual machine system provided with management programs which are used for running a plurality of operating systems parallelly at the same time.
In recent years, the concepts of virtual storage and virtual machines have been of increasing interest in the computing community. The virtual storage system may be defined generally as any information storage system in which there is, or may be, a distinction between the logical address generated by a program and the physical address for some real storage device from which information is actually fetched. Similarly, the virtual machine system may be defined as a computing system in which the instructions issued by a program may be different from those actually executed by the hardware to perform a given task. The above concepts of the virtual storage and virtual machines are very important when creating a large capacity computing system. In the present invention, the virtual machine is specifically referred to, rather than the virtual storage.
As will be explained hereinafter in detail, the virtual machine has an advantage in that, as compared to a conventional native machine, a plurality of programs, each of which runs in one of a corresponding plurality of operating systems, can be executed parallelly at the same time and also the organization of the computing system can be flexibly modified. However, the virtual machine has a disadvantage in that, as compared to the conventional native machine, the virtual machine often operates with a reduction of capacity due to the occurrence of so-called overhead.